The invention relates to an ignition system for a four-stroke rotary piston combustion engine of the trochoid type. The shell of the engine has an inner chamber bounded by a mantle with dual-arc inside contour through which an eccentric shaft with an eccentric passes. A triangular piston is rotatably mounted on the eccentric shaft. Two or more spark plugs are fitted in the mantle in the area near the shaft and the spark plugs are connected to their own ignition generator in an ignition system.
In rotary piston combustion engines of the above type there is a relatively elongated combustion chamber at the time of ignition, due to the sickle-shaped configuration of the working chamber. This combustion chamber shape may make complete combustion of the gases difficult. By using several spark plugs which ignite simultaneously or sequentially, conventional ignition systems aim to prevent a dragging and incomplete combustion of the aspired gases and thus to reduce the initially caused high specific fuel consumption as well as the amount of harmful ingredients in the exhaust gas. One of the well-known supplementary measures is to provide a control system that causes ignition of the individual spark plugs at different times. This measure may make a marked improvement in the temporal course of the combustion. It has been found, however, that in conventional ignition systems the usual coil ignition, of which the ignition spark has a long burning duration and which therefore improves the ignition of the gas -- which is a particular advantage under idling and partial-load operation -- will fail to perform properly if soot deposits on the spark plugs from the normally soot laden environment. In addition, coil ignition may occasionally miss at high rotation speeds. Magneto ignition systems, which are also quite well known, exhibit similar characteristics. The high-voltage capacitor ignition system -- which is also used -- on the other hand, ensures satisfactory ignition immediately after engine start, under conditions of hot running, and at high rotation speeds in a rotary piston combustion engine, even if the spark plugs are soot-laden. The reason for this is the fast voltage rise speed and the powerful ignition voltage pulse of these ignition systems. It is a definite advantage. However, the use of such an ignition system may be relatively expensive in cases where several spark plugs are employed in a rotary piston combustion engine in conjunction with a highvoltage capacitor ignition system. It is therefore evident that in a rotary piston combustion engine equipped only with a single specific ignition system, the advantages resulting from such a system are necessarily coupled with restrictions with respect to the ignition performance which, in turn, may affect adversely the combustion process in certain operating ranges.